Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/2805—Compounds having only one group containing active hydrogen
  • C08G18/285—Nitrogen containing compounds
  • C08G18/286—Oximes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/08—Processes
  • C08G18/0804—Manufacture of polymers containing ionic or ionogenic groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/08—Processes
  • C08G18/0804—Manufacture of polymers containing ionic or ionogenic groups
  • C08G18/0819—Manufacture of polymers containing ionic or ionogenic groups containing anionic or anionogenic groups
  • C08G18/0823—Manufacture of polymers containing ionic or ionogenic groups containing anionic or anionogenic groups containing carboxylate salt groups or groups forming them
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/08—Processes
  • C08G18/10—Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/08—Processes
  • C08G18/10—Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
  • C08G18/12—Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step using two or more compounds having active hydrogen in the first polymerisation step
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G2170/00—Compositions for adhesives
  • C08G2170/80—Compositions for aqueous adhesives

Definitions

• the present invention relates to thermoreactive water-borne compositions based on stable polyurethane dispersions or solutions.
• the present invention relates to aqueous compositions based on prepolymers terminated with partially or totally blocked NCO groups.
• the present invention relates to systems in an aqueous dispersion or solution based on prepolymers terminated with partially or totally blocked NCO groups and containing hydrophilic groups, the process for their preparation and their use as binders for chipped/granular material, in the form of scraps too, or as adhesives, coatings and thermoreactive films.
• scraps materials for example grinded polyurethane foam, rubber flakes, chip boards, cork or other lignocellulosic material, and also the use of binders without solvents based on NCO-terminated prepolymers to produce composites mainly in the form of boards, sheets, panels, etc.
• binders are developed as an alternative to the known urea/formaldehyde resins, whose use is destined to decline owing to the fact that free formaldehyde causes problems of an environmental hygenic nature.
• the technology for the preparation of composites based on recycled waste materials involves agglomerating the granular material with binders without solvents based on prepolymers terminated with NCO groups and subjecting this to the action of heat under pressure in suitable moulds (thermocompression).
• the NCO groups react with the humidity present in the material or are reacted with water added during the preliminary impregnation phase or with vapour during the subsequent thermocompression phase.
• these binders also rapidly react with the humidity of the air in the enviroment, the agglomerate must be thermocompressed immediately after the impregnation phase.
• emulsifiable modified monomeric or polymeric MDI diphenylmethane diisocyanate
• MDI diphenylmethane diisocyanate
• lignocellulosic chips as described in published European patent applications 335.342, 354.516 and 13.112.
• These emulsions have a limited pot life (4-30 hours), are suitable for productions without interruption and also require the agglomerate to be thernocompressed immediately after the impregnation phase.
• Both of the binders described above release monomeric diisocyanates under heat and produce, after cross-linking, mainly polyureic bonds.
• compositions can be prepared, in the form of aqueous solutions or dispersions which are storage stable, starting from prepolymers with an isocyanic functionality of less than 12% by weight and that these compositions containing trimerization catalysts, after cross-linking under heat, produce elastomeric systems with surprising properties of mechanical resistance.
• thermoreactive aqueous compositions based on stable polyurethane dispersions or solutions comprising:
• the compounds of step (a) are obtained by the reaction of a polyisocyanate with a compound containing active terminal hydrogen atoms and with monofunctional blocking agents.
• Any polyisocyanate capable of giving NCO-terminated prepolymers can be used in the preparation of the compositions of the present invention, such as aliphatic, aromatic, arylaliphatic, cycloaliphatic polyisocyanates containing from 2 to 15 carbon atoms.
• low molecular weight polyisocyanates can be used, with a functionality equal to or higher than 2, for example between 2 and 4, possibly modified with urethane groups, carbodiimides, urethidinedione, urethone imine, isocyanurate, urea and biuret, etc.
• low molecular weight polyisocyanates are: 1,6-hexamethylenediisocyanate; 1,12-dodecanediisocyanate; meta and/or para-phenylenediisocyanate; 2,4-toluenediisocyanate alone or mixed with the isomer 2,6-toluenediisocyanate; 4,4'-diphenylmethandiisocyanate; possibly mixed with its 2,4' isomer; naphthalenediisocyanate; 2,4'-and/or 4,4'-dicyclohexylmethandiisocyanate; 1-isocyanate-3-isocyanatemethyl-3,3,5-trimethylcyclohexane or isophoronediisocyanate; 1,3- and/or 1,4-xylylene diisocyanate; para or meta tetramethylxylenediisocyanate; etc.
• Other examples of low molecular weight polyisocyanates are indicated in the published European patent application 32
• medium or high molecular weight polyisocyanates can be used at varying degrees of condensation such as those obtained by the phosgenation of aniline-formaldehyde condensates.
• examples are mixtures of polymethylenepolyphenylenepolyisocyanates having an average functionality of 2.6-2.9. These products are produced under various trade-names, for example "Tedimon 31" or “Tedimon 390" of ENICHEM.
• the preferred polyisocyanate of the present invention is however 2,4-toluenediisocyanate alone or mixed with at least 20% by weight of 2,6 isomer.
• the preferred compound containing terminal active hydrogen atoms of the present invention comprises:
• the polyols (1) have a molecular weight of between 62 and 10,000 and a nominal functionality of at least 2, preferably between 2 and 4. These compounds can be selected from polyol polyethers; polyol polyesters; mixed polyols containing ether and ester groups; polyether polyols containing terminal or in-chain aminic groups; polyols based on polylactone, polycarbonate, polyacrylate, polybutadiene; their mixtures; etc.
• Preferred products are polyol polyethers, also containing ester groups or terminal or in-chain aminic groups, obtained by the condensation of C 2 -C 6 olefin oxides on compounds (starters) having at least two active hydrogen atoms.
• Preferred C 2 -C 6 olefin oxides are ethylene oxide; propylene oxide; their mixtures containing ethylene oxide in a quantity of less than 95% by weight, preferably between 1 and 50%; butylene oxide; styrene oxide; tetrahydrofuran; epichlorohydrin; their mixtures; etc.
• the condensation takes place on starter such as glycols, triols, tetrols, etc. amines, alkanolamines and polyamines or their mixtures.
• polyol polyethers to be used according to the present invention are those terminated with propylene oxide or ethylene oxide and in which the starter is a glycol such as ethyleneglycol; 1,4-butandiol; 1,6-hexandiol; 1,8-octandiol; neopentyl glycol; diethyleneglycol; 1,3-propyleneglycol; dipropyleneglycol; a triol such as glycerine; trimethylolpropane; 1,2,4-trihydroxybutane; 1,2,6-trihydroxyhexane; 1,1,1-trimethylolethane; a tetrol such as pentaerythritol; or a polyfunctional hydroxyalkane such as xylitol; arabitol; sorbitol; mannitol; a diamine such as ethylenediamine; tetramethylene diamine; phenylene diamine; an alkanolmine such as
• the polyols and/or polyamines and/or monols containing hydrophilic groups (2) of the present invention support groups of the anionic or cationic type, in a quantity of between 5 and 150 meq for every 100 g of isocyanic prepolymer (a), and/or blocks of the non-ionic type.
• anionic groups carboxylate and sulfonate groups are preferred, supported by units having at least one reactive group towards the isocyanic groups such as diols, diamines or aminoalcohols, salified with a base, as described in published European patent application 537.578 or in German patent 3.903.538.
• a unit supporting an anionic hydrophilic group which is preferred according to the present invention is dimethylolpropionic acid salified with a neutralizing agent, for example an alkaline base such as sodium hydroxide; potassium hydroxide; or a tertiary amine such as triethylamine; N-methylmorpholine; etc.
• the preferred base is triethylamine used in such quantities as to give a ratio COOH/N or SO 3 H/N of between 1 and 1.2.
• Cationic groups which can be used are ammonium, sulfonium or phosphonium groups as described in published European patent application 537.578, in U.S. patent 4.408.008 and German patent 3.643.791.
• the units supporting these groups contain at least one reactive group towards the isocyanates.
• a preferred unit supporting a cationic hydrophilic group according to the present invention is N-methyldiethanolamine salified with a neutralizing agent, for example an organic acid such as acetic acid, or an inorganic acid such as phosphoric acid, or quaternized with an alkylating agent such as dimethylsulfate.
• Preferred salification ratio are basically the stoichiometric values.
• ethylene oxide blocks can be used. It is also possible to use non-ionic hydrophilic segments introduced into the isocyanic prepolymer structure as lateral or terminal chains as described in published European patent application 404.371 and in U.S. patent 4.408.008. Total quantities of ethylene oxide of between 0.1 and 40 parts by weight per 100 parts of component (a) are particularly suitable in the present invention.
• the compound containing terminal active hydrogen atoms can also comprise chain-extending agents (3) in a quantity of between 0 and 30%, in equivalents, of the total of (1)+(2)+(3).
• Chain-extending agents in polyurethanes is described in U.S. patents 3.233.025, 3.915.937, 4.065.410 and 4.048.105.
• Polyols with a molecular weight of less than 400 can be used as chain-extending agents such as: ethyleneglycol, propyleneglycol, trimethylolpropane, 1,4-butandiol, bisphenols, diethyleneglycol, dipropyleneglycol, glycerine, low molecular weight condensates of propylene oxide and/or ethylene oxide on ethylenediamine, etc., or their mixtures; or aliphatic polyamines with a molecular weight of less than 400 such as: ethylenediamine, diethylenetriamine, isophorondiamine, aminoethylethanolamine, diaminocyclohexane, hexamethylenediamine, bisesamethylenetriamine, aminoethylpiperazine, hydrazine, etc.
• reaction between the organic polyisocyanate and the compound containing chain-end active hydrogen atoms is carried out according to the known techniques illustrated in "Saunders & Frisch - Polyurethanes, Chemistry and Tecnology" Interscience, New York, 1964 and operating with such ratios between the reagents as to give a prepolymer with an isocyanic functionality having a content of NCO groups of less than 12% by weight, preferably between 3 and 11%.
• the NCO-terminated prepolymer contains at least 1.4% by weight of blocked isocyanic groups.
• Suitable blocking agents of the NCO groups are those indicated in "Progress in organic coatings" 3(1975) 73-99, in U.S. patents 4.524.104 and 5.157.074 or substituted pirazoles such as 3,5-dimethylpyrazole.
• blocking agents which are suitable for the preparation of the compositions of the present invention are secondary or tertiary alcohols such as isopropanol or t-butanol; oximes such as methylethylketoxime; cyclohexanone oxime; acetone oxime; lactams such as ⁇ -caprolactam; phenols such as nonylphenol; N-alkylamides such as N-methyl acetamide; imides such as phthalimide; imidazoles such as benzylimidazole; triazoles such as benzotriazole etc. Oximes, however, are preferred and in particular methylethylketoxime.
• the equivalent ratio between the blocking groups and the isocyanic groups is at least 0.12:1, preferably at least 0.4:1. Ratios of between 0.6:1 and 1.1:1 are those normally used.
• trimerization catalyst (b) selected, when the hydrophilic groups present in the prepolymer are anionic and/or non-ionic, from:
• trimerization catalysts suitable for the present invention are described in U.S. patent 5.157.074.
• Preferred catalysts are alkaline hydroxides (v).
• hydrophilic groups present in the prepolymer are of the cationic and/or non-ionic type trimerization catalysts must be used which are stable in an acid environment such as Lewis acids, for example iron or aluminium chloride, or organometallic catalysts, for example the halides of organic antimonium.
• the activity of the catalyst can be optionally increased by the use of a co-catalyst selected from the following groups: alkylene-carbonates, aldehydes, polyepoxides, oxazolines and carbodimides.
• a co-catalyst selected from the following groups: alkylene-carbonates, aldehydes, polyepoxides, oxazolines and carbodimides.
• polyepoxides are preferred.
• the catalyst is added in quantities of more than 0.05% by weight, with respect to the prepolymer (a), preferably between 0.1 and 20%, more preferably between 0.1 and 5%.
• compositions of the present invention enable the cross-linking process to be carried out even months after the impregnation, thus allowing the production of the thermoformable agglomerates to be run in a discontinuous way.
• compositions of the present invention can contain additives such as catalysts for the synthesis and blocking of the prepolymers, antisedimentation agents, thixotropic agents, bactericides, fungicides, wetting agents, thickening agents, antifoaming agents, adhesion promotors, flame-retardants, antioxidants, U.V.
• additives such as catalysts for the synthesis and blocking of the prepolymers, antisedimentation agents, thixotropic agents, bactericides, fungicides, wetting agents, thickening agents, antifoaming agents, adhesion promotors, flame-retardants, antioxidants, U.V.
• absorbers sterically hindered amines, viscosity regulators, fillers, pigments, etc.
• modifiers such as non-reactive "tackifier” resins for example, modified terpenephenolic resins or latexes with different chemical bases, co-reactive as latent extenders such as ketazines, ketimines and bis-oxazolidines to be used when the isocyanic prepolymer is only partially blocked.
• the total quantity of these optional components can vary from 0 to 80% by weight with respect to components (a) + (b).
• compositions of the present invention can be used as binders for inert materials in the form of particles or chips, as adhesives or paints.
• binders there is an impregnation phase of the inert material, preferably by spray, a forming phase of the article which is to be obtained and a cross-linking phase under heat and compression.
• An advantage of the compositions of the present invention is that the last two phases for the preparation of the article can be carried out at different times and, therefore, not necessarily made in a continuous way or just after the initial impregnation phase.
• the water compositions are applied with the traditional methods.
• the starting of the cross-linking process requires the supply of thermal energy which can be provided electrically, electromagnetically (induction), dielectrically or by means of infra-red rays, microwaves, vapour or thermal exchange.
• the unblocking temperatures of the isocyanic groups vary from room temperature to 250°C.
• An advantage of the present compositions in the field of paints or adhesives basically consists in the good filming and elastomeric properties of the thermoreactive system.
• a process for the preparation of the compositions of the present invention comprises:
• the blocking reaction (ii) can also take place before the polyaddition (i) or contemporaneously. In all cases the reactions can occur in mass or in solvent, for example acetone or N-methylpyrrolidone.
• the present invention comprises the reaction or extension of the free NCO groups either with the dispersion water itself or with compounds containing active hydrogens, more reactive than water, added to the dispersion.
• the salification reaction of the ionic groups can also take place during or after the preparation of the blocked prepolymer before dispersion in water.
• the dispersion phase in water is carried out so that there is a content of solids of between 10 and 60% by weight, preferably between 20 and 50%.
• Phase (iv) is not necessary when the salifying agent is in itself a trimerization catalyst.
• thermoreactive system which after evaporation of the water at 50°C for 24 hours and subsequent cross-linking for an hour at 150°C, has a thickness of about 200 micrometers and the characteristics indicated in Table 2, is poured into a mould treated with silicon release agent.
• the impregnation of flakes of flexible polyurethane foam (density: 40 Kg/m 3 ; flake dimension: 10 mm, max) is carried out by spraying the thermoreactive system under air pressure and maintaining a weight ratio between the solid binder and flakes of about 5/95. 70 g of the agglomerate are subsequently compressed under heat operating for 5 and 15 minutes respectively at 150°C at such a pressure as to obtain a density of the final product of about 400 Kg/m 3 .
• a second portion of agglomerate is left in the air for two months and is then thermocompressed.
• Tedimon 80 213 g of Tedimon 80 are charged, in a nitrogen atmosphere, into a reactor equipped with a stirrer and heat exchange devices, and 125 g of methylethylketoxime are fed, under stirring, in 60 minutes reaching a temperature of 65°C. This temperature is maintained for 20 minutes.
• 35 g of dimethylolpropionic acid are then charged under stirring and the temperature is increased to 120°C.
• the temperature is reduced to 65°C.
• 221 g of Tedimon 80 are fed in 35 minutes without ever exceeding 75°C.
• the mixture is then left to react for 3 and a half hours at 75°C under stirring.
• 100 g of the prepolymer of example 4, pre-heated to 70°C, are dispersed in an aqueous solution of 0.95 g of sodium hydroxide in 199.05 g of demineralized water, the addition being carried out slowly under stirring at 600 rpm and continuing the dispersion for a further 3 minutes at 800 rpm.
• the temperature is reduced to 65°C.
• 244 g of Tedimon 80 are fed in 35 minutes without ever exceeding 75°C.
• the mixture is then left to react for 3 and a half hours at 75°C under stirring.
• the addition is carried out slowly under stirring at 600 rpm and continuing the dispersion for a further 3 minutes at 800 rpm.
• TEDIMON 31 polymeric MDI with a functionality of 2.7 of Enichem S.p.A.
• a reactor equipped with a stirrer, heat exchange devices and a reflux condenser 200 g of butoxy polyalkyleneglycol with a molecular weight of 3400 based on ethylene oxide and propylene oxide in a ratio of 75/25, are slowly fed.
• the temperature is increased to 75°C and is maintained as such for 3 hours.
• 125 g of this prepolymer are dispersed in a water solution consisting of 178 g of water, 52.5 g of methylethylketoxime, 1.25 g of potassium hydroxide at 1%, 0.1 g of SILWET L77 (Union Carbide). The addition is carried out at room temperature over a period of two minutes under stirring at 650 rpm. After a further 3 minutes of stirring an exotherm effect is observed up to 37°C.
• the dispersion is diluted with water until there is a solid content of 28%.
• the dispersion thus obtained has a viscosity of 20 mPa*sec at 23°C and is immediately used as such.
• the results of the characterization are shown in Tables 1 and 2.
• thermoreactive systems of the previous examples are compared with a humidity curing commercial prepolymer of the conventional type used as a binder of scraps of flexible polyurethane foam, having the following characteristics:
• the flakes of flexible polyurethane foam are impregnated by pouring the prepolymer very slowly until a quantity of 9% by weight of the total has been fed. At the end of the addition a quantity of water equal to 0.5% is very slowly added to the agglomerate. The agglomerate is thermoformed after a few minutes following the same procedure as in example 1. The results are shown in Table 5.

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• Organic Chemistry (AREA)
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• Compositions Of Macromolecular Compounds (AREA)
• Polyurethanes Or Polyureas (AREA)

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Cited By (6)

Citations (3)

• 1995
  • 1995-05-05 IT ITMI950897A patent/IT1273616B/it active IP Right Grant
• 1996
  • 1996-04-10 ES ES96105607T patent/ES2146806T3/es not_active Expired - Lifetime
  • 1996-04-10 DE DE69608848T patent/DE69608848T2/de not_active Expired - Lifetime
  • 1996-04-10 DK DK96105607T patent/DK0741153T3/da active
  • 1996-04-10 EP EP96105607A patent/EP0741153B1/de not_active Expired - Lifetime
  • 1996-04-10 SI SI9630211T patent/SI0741153T1/xx unknown
  • 1996-04-10 AT AT96105607T patent/ATE193895T1/de not_active IP Right Cessation
  • 1996-04-10 PT PT96105607T patent/PT741153E/pt unknown
• 2000
  • 2000-06-21 GR GR20000401435T patent/GR3033740T3/el not_active IP Right Cessation

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